The invention relates generally to a method of forming a copper wiring in a semiconductor device, and more particularly to, a method of forming a copper wiring in a semiconductor device capable of not only realizing reappearance (also expressed as reproducibility) of the copper deposition process but also obtaining a copper thin film having a good film quality, by establishing a metal organic chemical vapor deposition (MOCVD) process technology in which 1,1,1,5,5,5-hexafluoro-2,4-pentadionato (3,3-dimethyl-1-butene)-copper(I) (hereinafter called (hfac)Cu(DMB)) compound is used as a copper precursor.
As semiconductor industries move into an ultra large scale integration, the geometry of devices reduces to a sub-half-micron region, while the circuit density thereof become increased in view of improved performance and reliability. Due to these reasons, a copper thin film is usually employed as an interconnection material useful in an integration circuit since the melting point of the copper thin film is higher than that of an aluminum thin film in forming a metal wiring in a semiconductor device. Thus interconnections made from copper thin film improves the reliability of a semiconductor device due to its higher resistance against electro-migration (EM) and also increases signal transfer speed due to its low resistivity.
In a method of forming a copper wiring, the copper deposition process is an important process in realizing higher device reliability and higher integrated device signal transfer speed. Thus, the copper deposition process employs various deposition methods such as physical vapor deposition (PVD), electroplating, electroless-plating and metal organic chemical vapor deposition (MOCVD). Because deposition methods, such as the MOCVD method, are significantly affected by a copper precursor, there is a need for a process that can easily deposit a copper precursor. Furthermore, a delivery system by which the copper can be safely moved must also be developed.
The MOCVD method of copper deposition may employ several types of liquid delivery systems (hereinafter called LDS), including: an LDS employing a bubbler method; an LDS such as direct liquid injection (hereinafter called DLI); an LDS such as control evaporation mixing (hereinafter called CEM); and an LDS having a vaporizer of an orifice type or a spray type. A compound comprising a copper metal called a precursor in an LDS is degraded to form a copper deposition.
In the copper precursor used in MOCVD, two compounds were developed. These compounds were copper II valence (Cu) compound such as 1,1,1,5,5,5,5-hexafluoro-2,4-pentadionato-copper(II) and Cu (hfac)2 compound, each having a low vapor pressure. Following the development of these two compounds, another compound, copper I valence (CUI), has been developed. Copper I valence (CUI) has a high deposition speed since it has a higher vapor pressure than the copper II valence compound and allows high quality copper thin film deposition at a low temperature of 150-250xc2x0 C. The 1,1,1,5,5,5-hexafluoro-2,4-pentadionato(trimethylvinylsilane)-copper(I) (hereinafter called (hfac)Cu(TMVS)) compound of the currently-developed various copper I valence compounds is a representative copper precursor for use in that has been widely used since it remains at a liquid phase at room temperature and allows a high quality copper thin film at a low temperature. Even with these advantages, however, the (hfac)Cu(TMVS) compound has a problem that it is degraded at room temperature. Thus, the (hfac)Cu(TMVS) compound has reappearance problems when applied to the process of manufacturing a semiconductor device. Accordingly, although the (hfac)Cu(TMVS) compound is high in vapor pressure among the developed several precursors, it is low in securing reappearance in the conventional LDS. As such, the (hfac)Cu(TMVS) compound will have great difficulty in securing reappearance unless a new LDS that can be safely carried is developed.
Further, as the range between the vaporization temperature and the condensation temperature in the (hfac)Cu(TMVS) compound is extremely narrow, there is a problem that it has to keep the temperature constant. Also, the (hfac)Cu(TMVS) compound can only be safely used for about one year if used with a stabilizer.
In order to solve the problems with in the (hfac)Cu(TMVS) compound, a (hfac)Cu(DMB) compound has been developed as a precursor. The (hfac)Cu(DMB) compound is a new compound that is developed using 3,3-dimethyl-1-butene (hereinafter called DMB) as Lewis base ligand. DMB used in this compound has a low molecular weight and high vapor pressure. Because the (hfac)CuODMB) compound uses DMB instead of a methyl group of VTMS as a Lewis base ligand, the compound has a higher vapor pressure than the (hfac)Cu(TMVS). Therefore, the (hfac)Cu(DMB) compound is a good precursor since it can significantly improve a poor deposition speed, which is one of the biggest problems in a MOCVD Cu precursor. However, because a MOCVD process technology using the (hfac)Cu(DMB) precursor in a conventional LDS has not been established, the (hfac)Cu(DMB) compound has not been commercialized.
It is therefore an object of the present invention to provide a method of forming a copper wiring in a semiconductor device capable of not only realizing reappearance of a copper deposition process without developing a new LDS, but also obtaining a copper thin film having a good film quality deposition process. This is performed by optimally setting the conditions of a copper deposition apparatus to establish a MOCVD process technology in which a (hfac)Cu(DMB) compound is used as a precursor.
In order to accomplish the above object, a method of forming a copper wiring in a semiconductor device according to the present invention is characterized in that it comprises the steps of forming an interlayer insulating film on a semiconductor substrate in which various components for forming a semiconductor device are formed; forming a contact hole and a trench on said interlayer insulating film and then forming a diffusion barrier layer on the surface of said interlayer insulating film including said contact hole and said trench; depositing Cu so that said contact hole and said trench can be sufficiently filled; using a (hfac)Cu(DMB) precursor by metal organic chemical vapor deposition (MOCVD) method in a bubbler provided with a reactive chamber, a direct liquid injection system, a control evaporation mixer or a liquid delivery system having a vaporizer of an orifice type or a spray type; and forming a copper wiring by performing a chemical mechanical polishing process.
In the case of using a bubbler provided with a reactive chamber, the temperature of a canister in the bubbler is in the range of 30-70xc2x0 C. The carrier gas induced into the canister of the bubbler is at least one of helium (He), hydrogen (H2), argon (Ar) and the flow rate thereof is in the range of 10-700 sccm. The temperature of all the gas lines and the source lines from the canister of the bubbler to the reactive chamber are kept the same as that of the canister of the bubbler. The internal temperature of the reactive chamber and the temperature of the showering head in the reactive chamber are kept the same as that of the canister of the bubbler.
In the case of using a direct liquid injection system provided with a reactive chamber, the temperature of the vaporizer in the direct liquid injection is in the range of 40-120xc2x0 C. The temperature of the carrier gas induced into the vaporizer of the direct liquid injection is controlled to be about 20xc2x0 C. higher than that of the vaporizer of the direct liquid injection. The carrier gas is at least one of helium (He), hydrogen (H2), argon (Ar) and the flow rate thereof is in the range of 10-700 sccm. The temperature of all the gas lines and the source lines from the vaporizer of the direct liquid injection to the reactive chamber are kept the same as that of the vaporizer. The internal temperature of the reactive chamber and the temperature of the showering head in the reactive chamber are kept the same as that of the vaporizer of the direct liquid injection.
In the case of using a control evaporation mixer provided with a reactive chamber, the temperature of a control valve in the vaporizer of the control evaporation mixer is kept at a room temperature. The temperature of a heat exchanger in the vaporizer is in the range of 40-120xc2x0 C. The temperature of the carrier gas induced into the control valve in the vaporizer of the control evaporation mixer is controlled to be 20-120xc2x0 C. lower or higher than that of the heat exchanger of the vaporizer. The carrier gas is at least one of helium (He), hydrogen (H2), argon (Ar) and the flow rate thereof is in the range of 10-700 sccm. The temperature of all the gas lines and the source lines from the vaporizer of the control evaporation mixer to the reactive chamber are kept the same as or 5-20xc2x0 C. higher than that of the heat exchanger of the vaporizer. The internal temperature of the reactive chamber and the temperature of the showering head are kept the same as that of the heat exchanger in the vaporizer of the control evaporation mixer.
In the case of using a liquid delivery system provided with a reactive chamber and having a vaporizer of an orifice type or a spray type, the temperature of the vaporizer is in the range of 20-120xc2x0 C. The temperature of the carrier gas induced into the vaporizer is controlled to be 40-140xc2x0 C. which is 20xc2x0 C. higher than that of the vaporizer. The carrier gas is at least one of helium (He), hydrogen (H2), argon (Ar) and the flow rate thereof is in the range of 10-700 sccm. The temperature of all the gas lines and the source lines from the vaporizer to the reactive chamber are kept the same as that of the vaporizer. The internal temperature of the reactive chamber and the temperature of the showering head are kept the same as that of the vaporizer.
Meanwhile, the (hfac)Cu(DMB) precursor can be used without any additives. However, when any additive is used in the (hfac)Cu(DMB) precursor, the DMB of 0.1-30% can be added or Hhfac of 0.1-20% can be added or a combination of DMB and Hhfac can be added, as a additive.